Generally, a pattern of a semiconductor device may be formed by coating a photoresist film on a layer, performing an exposing process on the photoresist film to form a photoresist pattern, and etching the layer using the photoresist pattern as an etch mask. Thus, in order to form the pattern having a desired shape, the photoresist pattern with a designed shape should be provided.
However, a spot may exist in the photoresist film. The spot may not be removed by the exposing process. The spot may cause inhomogeneity of the photoresist film. Therefore, the photoresist pattern may not have the desired shape due to a portion of the photoresist pattern where the spot may exist. As a result, in order to reduce the likelihood of an abnormal pattern being formed, it may be desirable to detect the inhomogeneity of the photoresist film.